In the LTE (Long Term Evolution) of the 3GPP (Third Generation Partnership Project), connection (establishment of connection at layers 1 and 2) between a user equipment (UE) and a radio base station (eNB (evolved Node B)) is performed by the following procedure.
1. Cell Discovery and Synchronization
The user equipment detects synchronization signals called the PSS (Primary Synchronization Signal) and the SSS (Secondary Synchronization Signal) sent from the radio base station, and identifies the subframe timing (subframe number) of the radio base station and the cell ID (PCI (Physical Cell ID)) of the radio base station.
2. Acquisition of System Information
The user equipment acquires system information necessary for connecting with the radio base station. The system information stimulated in the LTE includes the MIB (Master Information Block) and the SIBs (System Information Blocks), as described in Non-patent Document 1 (Section 7.4) and Non-patent Document 2 (Section 5.2). System information necessary for connecting with the radio base station includes the MIB, SIB1 (System Information Block Type 1), and SIB2. The MIB describes the bandwidth used by the radio base station, information necessary for receiving the PDCCH (physical downlink control channel), and the SFN (system frame number). SIB1 indicates restriction information indicating whether access to the radio base station by user equipments is currently permitted or inhibited, and schedule information on other SIBs. SIB2 indicates common channels for which the user equipment connects with the radio base station and information on the common channels.
The user equipment detects the MIB using the identified subframe timing, and acquires the bandwidth, information necessary for downlink reception, and the system frame number. Then, using information acquired from the MIB, the user equipment detects SIB1 and acquires the schedule information on other SIBs. Furthermore, using the information acquired from SIB1, the user equipment detects the other SIBs and acquires information for accessing the radio base station.
3. Radio Link Establishment According to Random Access Procedure
After acquisition of the system information, the user equipment sends a random access preamble to the radio base station, and receives a random access response from the radio base station. The user equipment also sends the ID of the user equipment itself, so that the radio base station solves collision of multiple user equipments even if multiple user equipments has sent the same preamble.